Hitherto, at conferences, academic conferences, exhibitions and the like, projectors have been in heavy usage.
As such projectors, for example, those constitutions and the like comprising an optical system, which modulates a light beam emitted from a light source and magnifies and projects it so as to form a projection image according to image information by using various optical parts, and an exterior case housing this optical system are known. Further, such an optical system is constituted by comprising an illumination optical system for subjecting the light beam emitted from a light source device including a light source lamp to an optical processing and an optical part housing for housing optical elements which constitute this illumination optical system.
In a polarizing conversion element which is one of such optical elements, the light beam emitted from the light source lamp is separated into two linear polarized lights of horizontal and vertical directions by a polarization beam splitter (PBS), and from among these polarized lights, the linear polarized light of the horizontal direction is converted into the linear polarized light of the vertical direction by a phase film. In this way, the light beam emitted from the light source device becomes the linear polarized light of a predetermined direction, thereby increasing a use efficiency of the light beam.
Such a polarizing conversion element is fabricated by gluing and connecting the polarization beam splitter and the phase film made of resin by an adhesive. For this reason, when an excessive heat is applied to the polarizing conversion element for a long period of time, the phase film made of resin is deformed or relative positions of the polarization beam splitter and the phase film are changed due to the hardening of the adhesive, thereby making it hard to perform a correct optical processing.
On the other hand, the light source device generates a high heat by emission of the light source lamp, and causes illumination optical elements such as the neighboring polarizing conversion element and the like to be heated. In view of these points, it becomes an important subject for study how effectively the polarizing conversion element and the light source device should be cooled.
Hence, to cool the optical system including the polarizing conversion element and the light source device, a cooling structure has been adopted, in which suction and exhaustion ports are formed in the exterior case which houses the optical system, and at the same time a fan is arranged in the interior thereof.
However, in the case of such a cooling structure, even though the whole optical system in the interior of the exterior case can be thoroughly cooled, there has been a problem in that the polarizing conversion element and the light source device which particularly require a cooling are not always sufficiently cooled.
Note that such a problem was not limited to the polarizing conversion element alone, but also occurred on other optical elements including a lens array and the like.
An object of the present invention is to provide a projector, which can sufficiently cool the optical elements and the light source device.